Conventionally, a cutting tool having a tip with a material of large hardness brazed and thus joined thereto, as represented by a cubic boron nitride (cBN) cutting tool, has been produced and utilized for cutting special steel and other various types of cutting.
Specifically, for example, a tool having cemented carbide and cBN brazed and thus joined together is produced and sold (e.g., IGETALLOY Cutting Tool ('07-'08 General Catalogue) issued by Sumitomo Electric Hardmetal Co., October, 2006, p. L4, Coated SUMIBORON Series (Non Patent Document 1)). Alternatively, a joined product formed by joining PCD (sintered diamond) or cBN and ceramics, cermet or cemented carbide by brazing has been proposed (e.g., Japanese Patent Laying-Open No. 2002-036008 (Patent Document 1) and Japanese Patent No. 3549424 (Japanese Patent Laying-Open No. 11-320218 (Patent Document 2)). In addition, a cutting tool formed by joining cemented carbide or cermet and high-speed steel or the like by brazing with a Cu brazing filler has also been proposed (e.g., Japanese Patent Laying-Open No. 11-294058 (Patent Document 3)).
In recent years, inter alia, a cutting tool having cemented carbide and cBN joined together attracts attention in particular.